In a radio communication system, a receiver receives simultaneously a signal which arrives directly (direct wave) from a transmitter and a signal which arrives after being reflected by obstacles (delay wave). Therefore, a frequency selective fading is generated due to multipath and hence reception quality is deteriorated.
In a multicarrier modulation, on the other hand, after dividing serial transmission data sequence into N pieces of data by serial to parallel conversion, each piece of data is modulated by a subcarrier wave of different frequency. Thus, even if the frequency selective fading due to multipath is generated, the probability that all data is lost can be reduced because transmission data is transmitted after being divided into a plurality of subcarrier waves of different frequencies in the multicarrier modulation method. That is, if the multicarrier modulation method is used, it will be hard to receive the influence of frequency selective fading.
However, because the symbol period is long in the aforementioned conventional multicarrier modulation method, the phase rotations and amplitude variations between symbols become relatively large. Consequently, in the case of a remarkably rapid fluctuation of the channel caused by fast fading, etc., the problem occurs that the channel estimation by an adaptive equalizer, etc., cannot fully follow the channel fluctuation which generates a deterioration of error characteristics.